U.S. Pat. No. 6,435,200 discloses an apparatus for etching a peripheral region of a disc-like article. The liquid is supplied to the surface of the disc-like article which does not face the chuck and is held in a gap between the disc-like article and a ring.
For specific application a mechanical force is advantageous in order to properly treat the peripheral region, e.g. in order to remove a specific layer from the peripheral region.